Find Poisson's Ratio of Aluminum from Torsion and Tensile Tests

In summary, the conversation discusses the shear modulus and modulus of elasticity of aluminum, as well as finding Poisson's Ratio. The formula for calculating Poisson's Ratio is provided and it is mentioned that it is a function of both strains and does not include modulus values. The conversation ends with James thanking Matt for the information.
  • #1
JPKelly
7
0
1. Torsion test showed aluminum to have shear modulus of 4.60x10^6psi. Under a tensile test, the same specimen showed a modulus of elasticity of 12.2x10^6psi. Find Poisson's Ratio.



2. Poisson's Ratio=lateral strain/axial strain



3. The ratio is a function of both strains. The equations for strain do not have any modulus values in them. I'm not asking for a total explanation, but more of a hint would help.

Thanks,
James
 
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  • #2
The shear modulus formula will allow you to calculate Poisson's Ratio.

G = E/(2*(1+v))

Where G is the shear modulus, E is the modulus of Elasticity, and v is Poisson's Ratio.

Thanks
Matt
 
Last edited:
  • #3
Thank you so much! I actually discovered that shortly after I posted the thread.

Thank you again.
James
 

1. What is Poisson's ratio and why is it important in material testing?

Poisson's ratio is the ratio of lateral strain to axial strain in a material under stress. It is an important parameter in material testing because it measures the material's ability to deform in response to external forces. This information is crucial in determining the material's mechanical properties and its suitability for certain applications.

2. How is Poisson's ratio determined from torsion and tensile tests?

In torsion testing, Poisson's ratio is calculated by measuring the change in diameter of a cylindrical sample as it is twisted along its length. In tensile testing, Poisson's ratio is calculated by measuring the change in width of a rectangular sample as it is stretched along its length. Both of these measurements are compared to the change in length of the sample to determine the ratio.

3. What factors can affect the accuracy of Poisson's ratio measurements?

The accuracy of Poisson's ratio measurements can be affected by several factors, including the sample's geometry, the type of loading applied, and the testing conditions (such as temperature and humidity). It is important to carefully control these variables in order to obtain accurate and reliable results.

4. How does Poisson's ratio vary between different materials?

Poisson's ratio can vary significantly between different materials. For example, it is generally higher in ductile materials and lower in brittle materials. It also depends on the microstructure and composition of the material. For aluminum, Poisson's ratio is typically around 0.33 to 0.35.

5. What are some practical applications of knowing Poisson's ratio for aluminum?

Knowing Poisson's ratio for aluminum can be useful in a variety of applications, such as in designing structures or components that require specific levels of stiffness and flexibility. It can also be used in predicting the behavior of aluminum under different types of stress and in determining its suitability for different manufacturing processes.

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